Final answer:
A manometer is a device used to measure the pressure of a gas trapped in a container and comes in closed-end and open-end varieties. A barometer, which is another type of pressure-measuring device, measures atmospheric pressure and is different from a manometer.
Step-by-step explanation:
In physics, a fixed orifice, variable pressure measuring or metering device is commonly known as a manometer. Manometers are used to measure the pressure of a gas trapped in a container. There are two types of manometers: the closed-end manometer and the open-end manometer. A closed-end manometer is a U-shaped tube with one closed arm and one arm that connects to the gas. The pressure of the gas is indicated by the distance between the liquid levels in the two arms of the tube. An open-end manometer is similar, but one of its arms is open to the atmosphere, allowing it to measure the difference in pressure between the gas and the atmospheric pressure.
On the other hand, a barometer is a device used to measure atmospheric pressure, which can also be made using a U-shaped tube filled with mercury. When atmospheric pressure changes, the mercury level rises or falls, providing weather forecasters with important information. It is important not to confuse a manometer with a barometer, thermometer, or hygrometer as each measures different physical properties.